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2 results on '"major storms"'

1. Spatial and Temporal Patterns of δ13C and δ15N of Suspended Particulate Organic Matter in Maryland Coastal Bays, USA

Author

Blessing O. Edje, Ali B. Ishaque, and Paulinus Chigbu

Subjects
stable isotopes, suspended particulate matter, lagoons, major storms, freshwater discharge, Hydraulic engineering, TC1-978, Water supply for domestic and industrial purposes, TD201-500
Abstract

The suspended particulate organic matter (SPOM) in transitional waters such as the Maryland Coastal Bays (MCBs) is derived from allochthonous and autochthonous sources. Little is known, however, about the contribution of terrestrially derived organic matter to SPOM in the MCBs. The sources of SPOM in the MCBs were evaluated using stable isotope ratios of nitrogen (δ15N) and carbon (δ13C), and C/N molar ratios. The values of SPOM δ15N, δ13C and C/N ratios from samples collected seasonally (July 2014 to October 2017) at 13 sites ranged from −0.58 to 10.51‰, −26.85 to −20.33‰, and 1.67 to 11.36, respectively, indicating a mixture of terrestrial SPOM transported by tributaries, marine organic matter from phytoplankton, and sewage. SPOM δ13C levels less than −24‰, suggesting the dominance of terrestrially derived carbon, occurred mainly at sites close to the mouths of tributaries, and were less depleted at sites near the ocean. The mean value of SPOM δ13C was higher in October 2014 (−22.76‰) than in October 2015 (−24.65‰) and 2016 (−24.57‰) likely due to differences in river discharge. Much lower values (15N observed in February 2016 coincided with a high freshwater inflow that accompanied a major storm, indicating a strong influence of untreated sewage. Results from a two end-member mixing model suggest that on average, the SPOM in the MCBs is composed of 44% terrestrial materials with the highest percent contributions in October 2015 and 2016 (61%), and lowest (28%) in July 2015. The contribution of terrestrial materials to the SPOM was highest (58%) near the mouth of St. Martin River and lowest (25%) near the Ocean City inlet. SPOM composition and distribution in MCBs are, therefore, a function of land use, freshwater inflow, and water circulation that influence in situ phytoplankton production, and the transport and distribution of terrestrially derived materials.

Published
2020
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2. Spatial and Temporal Patterns of δ13C and δ15N of Suspended Particulate Organic Matter in Maryland Coastal Bays, USA

Author

Paulinus Chigbu, Blessing O. Edje, and Ali B. Ishaque

Subjects
0106 biological sciences, lcsh:Hydraulic engineering, Freshwater inflow, 010504 meteorology & atmospheric sciences, Geography, Planning and Development, stable isotopes, Aquatic Science, 01 natural sciences, Biochemistry, lcsh:Water supply for domestic and industrial purposes, lcsh:TC1-978, lagoons, Phytoplankton, Tributary, Organic matter, 0105 earth and related environmental sciences, Water Science and Technology, chemistry.chemical_classification, lcsh:TD201-500, geography, geography.geographical_feature_category, δ13C, Discharge, 010604 marine biology & hydrobiology, freshwater discharge, δ15N, Particulates, suspended particulate matter, major storms, Oceanography, chemistry, Environmental science
Abstract

The suspended particulate organic matter (SPOM) in transitional waters such as the Maryland Coastal Bays (MCBs) is derived from allochthonous and autochthonous sources. Little is known, however, about the contribution of terrestrially derived organic matter to SPOM in the MCBs. The sources of SPOM in the MCBs were evaluated using stable isotope ratios of nitrogen (&delta, 15N) and carbon (&delta, 13C), and C/N molar ratios. The values of SPOM &delta, 15N, &delta, 13C and C/N ratios from samples collected seasonally (July 2014 to October 2017) at 13 sites ranged from &minus, 0.58 to 10.51&permil, &minus, 26.85 to &minus, 20.33&permil, and 1.67 to 11.36, respectively, indicating a mixture of terrestrial SPOM transported by tributaries, marine organic matter from phytoplankton, and sewage. SPOM &delta, 13C levels less than &minus, 24&permil, suggesting the dominance of terrestrially derived carbon, occurred mainly at sites close to the mouths of tributaries, and were less depleted at sites near the ocean. The mean value of SPOM &delta, 13C was higher in October 2014 (&minus, 22.76&permil, ) than in October 2015 (&minus, 24.65&permil, ) and 2016 (&minus, 24.57&permil, ) likely due to differences in river discharge. Much lower values (&lt, 4&permil, ) of &delta, 15N observed in February 2016 coincided with a high freshwater inflow that accompanied a major storm, indicating a strong influence of untreated sewage. Results from a two end-member mixing model suggest that on average, the SPOM in the MCBs is composed of 44% terrestrial materials with the highest percent contributions in October 2015 and 2016 (61%), and lowest (28%) in July 2015. The contribution of terrestrial materials to the SPOM was highest (58%) near the mouth of St. Martin River and lowest (25%) near the Ocean City inlet. SPOM composition and distribution in MCBs are, therefore, a function of land use, freshwater inflow, and water circulation that influence in situ phytoplankton production, and the transport and distribution of terrestrially derived materials.

Published
2020

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